Gas Insulated or Air Insulated Switchgear 

By on

Various arguments exist around SF6 Gas Insulated (GIS) and Air Insulated (AIS) switchgear. Recently we had to change a GIS design to AIS due to an instruction from one of  our clients.  His concern is the global warming potential of SF6.   While understanding the clients reasons, I'm not convinced on the argument.

General arguments in favour of GIS include:

  • GIS is more cost effective
  • requires less space (up to 70% less that Air Insulated)
  • is safer in operation
  • has overall lower system loses
  • has higher protection against ambient conditions
  • is more reliable

As far as I can see the main argument against SF6 is that it has a global warming potential.  From an environmental view, the potential of releasing gas which contributes to global warming is obviously bad.  However, to quantify the effect, Capiel (see link below) has carried out some research:

  • GIS switchgear emissions (Europe, 2002) contribute 0.05% to total greenhouse gas emissions
  • measures implemented in switchgear design since 1995 have reduced GIS gas emissions by 40%
  • there is continuing technological progress in further reducing GIS gas emissions

Key Question

I think the key question in all of this is:

  • do the benefits of a safe reliable, cost effective electrical supply networks outweigh the potential SF6 contribution to greenhouse gas emissions ?

My View

The direct contribution of SF6 to greenhouse gas emissions is relatively low and I tend to think the advantages of a reliable electrical system outweigh these negatives.  Lower system loses and less materials required during manufacture reduce the life cycle carbon emissions, potentially offsetting the negative effects of SF6. 

A life cycle analysis of the German distribution system by Capiel (see link below) which considers materials, manufacture, ohmic losses and SF6 emissions shows that overall GIS contributes 30% less to global warming than AIS. Currently the arguments given against GIS don't appear sufficiently thought out and consider only the SF6 emission issue.

Without closing the door on the debate, I don't see enough evidence to force move away from GIS to AIS. 

Related Links



Steven McFadyen's avatar Steven McFadyen

Steven has over twenty five years experience working on some of the largest construction projects. He has a deep technical understanding of electrical engineering and is keen to share this knowledge. About the author

myElectrical Engineering

comments powered by Disqus



Software Usage Guidelines

Using software in our  work is essential for most of us and we are becoming even more dependant on it's use.  While software is a great asset, many times...

Mobile Phones (Brick to Implant)

The mobile phone was born in 1973. They were the size of a brick and weighed a couple of kg, making them difficult to fit into your pocket. At a few thousand...

UPS Battery Sizing

Various techniques exist to enable the correct selection of batteries for UPS applications.  The procedure described below is one of the more common. ...

Hazardous Areas – IEC and NEC/CEC Comparison

Depending where in the world you work, you are likely following one of two standards International Electrotechnical Commission (IEC) National...

Inductance

When current flows within a wire, a magnetic field is created. The potion of this magnetic field perpendicular to the wire is called the magnetic flux...

EU Code of Conduct on Data Centres - Best Practices

The European Union is implementing a voluntary code of practice for participants with the aim of improving the overall efficiency of data centres. As part...

Operational Amplifier

The fundamental component of any analogue computer is the operational amplifier, or op amp. An operational amplifier (often called an op-amp,) is a high...

Cable Sizing Tool

Our cable sizing tool is one of the more popular tools on the site.  The tool enables cables to be sized in compliance with BS 7671 (the IEE Wiring Regulations...

The ac resistance of conductors

In a previous article I looked at the dc resistance of conductors and in this article we turn our attention to ac resistance. If you have not read the...

DC Component of Asymmetrical Faults

The image (reproduced from IEC 60909) shows a typical fault in an ac system.  From the illustration it can seen that there is an initial dc component ...

Have some knowledge to share

If you have some expert knowledge or experience, why not consider sharing this with our community.  

By writing an electrical note, you will be educating our users and at the same time promoting your expertise within the engineering community.

To get started and understand our policy, you can read our How to Write an Electrical Note